P. mexicanus species group. Formerly classified as a subspecies of P. mexicanus (Osgood, 1909); Musser (1971) elevated gymnotis to species and pointed out the junior status of allophylus. Differentiation from P. mexicanus sustained by Huckaby (1980) and Jones and Yates (1983), who also amplified the southern range and morphological recognition of P. gymnotis. As noted by Carleton (1989), the northward distribution in the region of the Isthmus of Tehuantepec now needs clarification, particularly in light of the report of a mexicanus sample from near Berriozábal, Chiapas, that genetically links with P. gymnotis (Rogers and Engstrom, 1992).